The present invention relates to electronics assemblies, and is primarily concerned with racked assemblies. Many such assemblies will be located in racks for housing in for example nineteen inch cabinets, or other size cabinets such as twenty three inch or metric cabinets. The assemblies may for instance be employed as servers for a number of systems, for example in local area networks (LANs), wide area networks (WANs), telecommunications systems or other operations such as database management or as internet servers.
Such an assembly will typically comprise a supporting frame that houses a motherboard or backplane and a number of daughterboards or module cards that extend in planes generally perpendicular to the plane of the motherboard and which are connected to the motherboard by connectors, e.g. high density connectors, so that the daughterboards can simply be introduced into the frame through an opening therein opposite the motherboard, located on guides and pushed toward the motherboard in order to connect them to it.
Each daughterboard usually requires multiple electrical connections which are generally provided by two-part multi-pin electrical connectors, one part of which is located at the rear of the daughterboard and the other part provided on the motherboard.
In order to engage the daughterboard and the motherboard connectors properly during insertion, and to aid removal of the daughterboards, it is common to employ injector/ejector mechanisms. An injector/ejector mechanism is operated by a user and is intended to ensure an appropriate even force to be applied to the electrical connectors between the motherboard and the daughterboards during insertion of the daughterboard, to lock the daughterboard in place during operation of the system and to aid disconnection of the electrical connectors during removal of the daughterboard. The most common form of injector/ejector mechanism comprises a lever arm that can be pivotally located on a flange on the frame at or adjacent to the opening or, more usually, located on the daughterboard and engage the flange, in order to provide a mechanical advantage during connection or disconnection.
One problem that has been encountered with such assemblies, however, is ensuring correct electrical connection between the daughterboards and the motherboard due to dimensional tolerances in the daughterboards and other parts of the assembly. The daughterboards may, for example, have typical dimensions in the region of 500 mm in the insertion and removal direction whereas the connectors may have a length of travel between initial contact of the pins and complete mating of the connectors, or so-called “wipe”, as low as 0.5 to 0.8 mm, with the result that because of tolerances in the length of the daughterboards, some connectors may be overstressed while other connectors may not form a good connection. This problem is particularly severe if daughterboards toward the end of an array are relatively long and cause the flange to bow, while daughterboards at the centre of the array are relatively short.
This problem may be resolved by providing a flexible coupling in the injector/ejector mechanism to allow relative movement of a daughterboard away from the motherboard while applying a biasing force toward the motherboard. Although such a system is perfectly adequate in resolving the problem, it requires discrete components to be incorporated in each injector/ejector mechanism and is therefore relatively expensive to implement.